External directional microphones for hearing devices are known. These external directional microphones transmit signals with an improved signal to noise ratio wirelessly to the corresponding hearing devices. They generally have an on/off switch and a switch for adjusting the nature or strength of the directional effect. A hearing device with an external directional microphone is for example known from WO 2004/093487 A2.
A circuit arrangement for switching mobile devices, for example hearing aids, on and/or off automatically is known from DE 40 34 096 A1. This known arrangement has a movement detector that detects a change in orientation or inclination. This known orientation sensor supplies an alternating signal to a circuit. The alternating signal indicates that the hearing aid is moving, as a result of which its orientation is changing. The circuit only switches the power supply on when an alternating signal from the orientation sensor is present. The power supply is switched off again, when no alternating signal from the orientation sensor is present for a specific time period.
A personal location device is known from DE 696 05 773 T2, with which an angle is generally measured between the direction from which a source emits electromagnetic, infrared or ultrasonic radiation and the direction in which a person has oriented their head.